Joanna, Duchess of Brabant (24 June 1322 – 1 November 1406), also known as Jeanne, was the heiress of Duke John III, who died in Brussels, December 5, 1355. Her mother was Marie d'Évreux.

Joanna's first marriage, in 1334, was to William IV, Count of Holland (1307–1345), who subsequently died in battle and their only son William died young, thus foiling that project of unifying their territories.

Her second marriage was to Wenceslaus of Luxemburg. The famous document, the foundation of the rule of law in Brabant called the Blijde Inkomst ("Joyous Entry"), was arrived at in January 1356, in order to assure Joanna and her consort peacable entry into their capital and to settle the inheritance of the Duchy of Brabant on her "natural heirs", who were Joanna's sisters, they being more acceptable to the burghers of Brabant than rule by the House of Luxembourg.

The document was seen as a dead letter, followed by a military incursion in 1356 into Brabant by Louis II of Flanders, who had married Margaret, Joanna's younger sister, and considered himself Duke of Brabant by right of his wife. With the Duchy overrun by Louis' forces, Joanna and Wencelaus signed the humiliating Treaty of Ath, which ceded Malines and Antwerp to Louis. By August 1356 Joanna and Wencelaus had called upon the Emperor, Charles IV to support them by force of arms. Charles met at Maastricht with the parties concerned, including representatives of the towns, and all agreed to nullify certain terms of the Blijde Inkomst, to satisfy the Luxembourg dynasty.The duchy continued to deteriorate with Wencelaus' defeat and captured at the battle of Baesweiler in 1371.

Her tomb was not erected in the Carmelite church in Brussels until the late 1450s; it was paid for in 1459 by her sister's grandson, Philip the Good. Though it was destroyed in the course of the French Revolutionary Wars, its appearance has been reconstructed from drawings and descriptions by Lorne Campbell, who concluded that the tomb was an afterthought, providing an inexpensive piece of propaganda for Philip's dynastic rights.